Seat structure and device for determining load on seat

Abstract

The seat structure includes a torsion bar as an elastic supporting-mechanism for elastically supporting a cushioning member, and is provided with arms and a supporting frame pivoted by the torsion bar. Accordingly, a device for determining a load on the seat can be structured with an extremely simple structure by providing a displacement detecting mechanism to detect the amount of twist or the twist angle of the torsion bar, or a pivot angle of the arm, displaced by being seated.

1. A seat structure comprising a cushioning member strained over a seat cushion via an elastic supporting-mechanism, wherein
 said elastic supporting-mechanism is structured including a torsion bar disposed in the rear of a seat cushion and a supporting frame connected to the torsion bar and biased to tilt backwards in a normal state; 
 said supporting frame is supported via an arm connected to said torsion bar; 
 said cushioning member is supported by said supporting frame, and strained by the elastic force of said torsion bar; and 
 a displacement detecting mechanism is provided for detecting displacement of said elastic supporting-mechanism when a load is applied to said cushioning member, so that the load applied to the cushioning member is detectable from a displacement signal detected by the displacement detecting mechanism. 
 
   
   
     2. The seat structure according to  claim 1 , wherein said displacement detecting mechanism is composed of a combination of a magnet and a magnetic sensor which changes its output characteristics according to the magnetic flux density of the magnet, and one is mounted on said arm member and the other is mounted on a frame member forming the seat cushion. 
   
   
     3. The seat structure according to  claim 1 , wherein said displacement detecting mechanism is structured to include a strain gauge mounted on said torsion bar to measure the amount of twist in the torsion bar with the strain gauge. 
   
   
     4. The seat structure according to  claim 1 , wherein said displacement detecting mechanism is structured to include an angle sensor connected to a movable end of said torsion bar to measure the twist angle of the torsion bar with the angle sensor. 
   
   
     5. The seat structure according to  claim 2 , wherein said magnetic sensor is a Hall IC. 
   
   
     6. A device for determining a load on the seat provided on a seat structure comprising: a torsion bar disposed in the rear of a seat cushion; and a supporting frame connected to the torsion bar and biased to tilt backwards in a normal state, and structured that a cushioning member is supported by said supporting frame and strained by the elastic force of said torsion bar, comprising:
 a displacement detecting mechanism to detect displacement of said elastic supporting-mechanism when a load is applied to said cushioning member, so that the load applied to the cushioning member is determined from a displacement signal detected by the displacement detecting mechanism. 
 
   
   
     7. The device for determining a load on the seat according to  claim 6 , wherein said displacement detecting mechanism is structured to include a strain gauge mounted on said torsion bar to measure the amount of twist in the torsion bar with the strain gauge. 
   
   
     8. The device for determining a load on the seat according to  claim 6 , wherein said displacement detecting mechanism is structured to include an angle sensor connected to a movable end of said torsion bar to measure the twist angle of the torsion bar with the angle sensor. 
   
   
     9. The device for determining a load on the seat according to  claim 6 , wherein said displacement detecting mechanism comprises a combination of a magnet and a magnetic sensor which changes its output characteristics according to the magnetic flux density of the magnet, and one is mounted on the arm member connected to said torsion bar and the other is mounted on a frame member forming the seat cushion.